Furniture doors and construction doors can be classified into a hinged door type, a sliding door type or the like. The hinged door is a door that opens by rotating. The sliding door opens and closes by horizontally sliding on a frame composed of a head jamb and a doorsill.
In order to assist opening and closing of such a door, there is provided a door opening and closing device. The door opening and closing device is mounted on either a door or a frame surrounding the door, and cooperates with a catch, which is mounted on the other of the door and the frame, to attenuate impact when the door gets closed forcefully by wind or the like or to assist a half-open door to be closed completely.
As such a door opening and closing device, the patent literature 1 discloses a door opening and closing device for opening and closing a door with use of a rack and pinion mechanism in a main structure. When the door gets closed and the catch of the door abuts to a catcher member of the door opening and closing device, the catcher member catches the catch and retracts it to a retraction position. A force for the catcher member retracting the catch results from a spring force of a helical extension spring. The spring force of the helical extension spring is converted into a retraction force of the catcher member by the rack and pinion mechanism.
The patent literature 2 discloses a door opening and closing device for opening and closing a sliding door. In such a door opening and closing device, when the sliding door gets closed, a crank arm catches a catch of the sliding door and retracts the sliding door to a retraction position. A force for the crank arm retracting the sliding door results from a spring force of a helical extension spring connected to the crank arm. The helical extension spring is directly connected to the crank arm and gives the crank arm a force in the retracting direction.